Adding a shower to downstairs cloakroom Drainage and wastage systems and plumbing help, advice and answers

[greendog]

Hi, I need to add a shower to a downstairs bathroom. In the corner of the bathroom is a grey soil stack 1000 mm high. Do I need to increase the height of this stack to allow for the shower and if so how high do I need to go?

Also, the toilet and existing basin are connected to this stack, with the basin outlet connected at 150 mm and a blank socket in the stack underneath. Ideally I want to install a walk in shower as my elderly mother will use this bathroom, but how can I get the shower to drain at what would be below floor level in a concrete floor? Even the lower socket won't be low enough.

I am grateful for any help you can give

[rosebery]

"Hi, I need to add a shower to a downstairs bathroom. In the corner of the bathroom is a grey soil stack 1000 mm high. Do I need to increase the height of this stack to allow for the shower and if so how high do I need to go?"

Is this a vent for the soil stack with an AAV (Durgo valve) on top? As the shower outlet will be below the level of the basin outlet and that is the critical measurement for the height of an AAV then no you should not need to increase it.

"Also, the toilet and existing basin are connected to this stack, with the basin outlet connected at 150 mm and a blank socket in the stack underneath. Ideally I want to install a walk in shower as my elderly mother will use this bathroom, but how can I get the shower to drain at what would be below floor level in a concrete floor? Even the lower socket won't be low enough."

Unfortunately you have to have a fall on the shower waste for it to operate correctly. Additionally you need to be able to access the waste trap (which should have an anti-vac device as well. That means raising the shower on a small plinth, running the waste above floor level and boxing it in afterwards. Digging up the concrete doesn't seem to be a suitable option if it then gives you problems with accessing the spare socket on the stack. Is any part of the stack accessible outside the buildng. If it is you could consider a walk in and take the waste out through the wall and join to the stack outside. Alternatively do you have an alternative foul water (you may not connect the shower to surface water drainage unless it is an old building and both foul and surface water go into the same sewer) waste (eg kitchen) that you can join the shower waste to outside?

Cheers

[greendog]

Thanks roseberry

That all makes sense. I have not been able to carry on with the project until this weekend. I will raise the shower tray and that should solve the drainage problem. I now have to decide on the type of shower, hopefully the forum will have lots of advice on that.
thanks again